From ea2dd8c1ed0becee9812cf0840a9cd553ed398fe Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Wed, 20 Mar 2013 17:21:28 +0000 Subject: dm cache: policy ignore hints if generated by different version When reading the dm cache metadata from disk, ignore the policy hints unless they were generated by the same major version number of the same policy module. The hints are considered to be private data belonging to the specific module that generated them and there is no requirement for them to make sense to different versions of the policy that generated them. Policy modules are all required to work fine if no previous hints are supplied (or if existing hints are lost). Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon --- drivers/md/dm-cache-metadata.c | 47 +++++++++++++++++++++++++++++++++--------- drivers/md/dm-cache-metadata.h | 2 +- drivers/md/dm-cache-target.c | 3 +-- 3 files changed, 39 insertions(+), 13 deletions(-) diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c index 74213d1f1db..83e995fece8 100644 --- a/drivers/md/dm-cache-metadata.c +++ b/drivers/md/dm-cache-metadata.c @@ -863,18 +863,43 @@ struct thunk { bool hints_valid; }; +static bool policy_unchanged(struct dm_cache_metadata *cmd, + struct dm_cache_policy *policy) +{ + const char *policy_name = dm_cache_policy_get_name(policy); + const unsigned *policy_version = dm_cache_policy_get_version(policy); + size_t policy_hint_size = dm_cache_policy_get_hint_size(policy); + + /* + * Ensure policy names match. + */ + if (strncmp(cmd->policy_name, policy_name, sizeof(cmd->policy_name))) + return false; + + /* + * Ensure policy major versions match. + */ + if (cmd->policy_version[0] != policy_version[0]) + return false; + + /* + * Ensure policy hint sizes match. + */ + if (cmd->policy_hint_size != policy_hint_size) + return false; + + return true; +} + static bool hints_array_initialized(struct dm_cache_metadata *cmd) { return cmd->hint_root && cmd->policy_hint_size; } static bool hints_array_available(struct dm_cache_metadata *cmd, - const char *policy_name) + struct dm_cache_policy *policy) { - bool policy_names_match = !strncmp(cmd->policy_name, policy_name, - sizeof(cmd->policy_name)); - - return cmd->clean_when_opened && policy_names_match && + return cmd->clean_when_opened && policy_unchanged(cmd, policy) && hints_array_initialized(cmd); } @@ -908,7 +933,8 @@ static int __load_mapping(void *context, uint64_t cblock, void *leaf) return r; } -static int __load_mappings(struct dm_cache_metadata *cmd, const char *policy_name, +static int __load_mappings(struct dm_cache_metadata *cmd, + struct dm_cache_policy *policy, load_mapping_fn fn, void *context) { struct thunk thunk; @@ -918,18 +944,19 @@ static int __load_mappings(struct dm_cache_metadata *cmd, const char *policy_nam thunk.cmd = cmd; thunk.respect_dirty_flags = cmd->clean_when_opened; - thunk.hints_valid = hints_array_available(cmd, policy_name); + thunk.hints_valid = hints_array_available(cmd, policy); return dm_array_walk(&cmd->info, cmd->root, __load_mapping, &thunk); } -int dm_cache_load_mappings(struct dm_cache_metadata *cmd, const char *policy_name, +int dm_cache_load_mappings(struct dm_cache_metadata *cmd, + struct dm_cache_policy *policy, load_mapping_fn fn, void *context) { int r; down_read(&cmd->root_lock); - r = __load_mappings(cmd, policy_name, fn, context); + r = __load_mappings(cmd, policy, fn, context); up_read(&cmd->root_lock); return r; @@ -1085,7 +1112,7 @@ static int begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *po (strlen(policy_name) > sizeof(cmd->policy_name) - 1)) return -EINVAL; - if (strcmp(cmd->policy_name, policy_name)) { + if (!policy_unchanged(cmd, policy)) { strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name)); memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version)); diff --git a/drivers/md/dm-cache-metadata.h b/drivers/md/dm-cache-metadata.h index 135864ea0ee..f45cef21f3d 100644 --- a/drivers/md/dm-cache-metadata.h +++ b/drivers/md/dm-cache-metadata.h @@ -89,7 +89,7 @@ typedef int (*load_mapping_fn)(void *context, dm_oblock_t oblock, dm_cblock_t cblock, bool dirty, uint32_t hint, bool hint_valid); int dm_cache_load_mappings(struct dm_cache_metadata *cmd, - const char *policy_name, + struct dm_cache_policy *policy, load_mapping_fn fn, void *context); diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c index ff267db6002..66120bd46d1 100644 --- a/drivers/md/dm-cache-target.c +++ b/drivers/md/dm-cache-target.c @@ -2369,8 +2369,7 @@ static int cache_preresume(struct dm_target *ti) } if (!cache->loaded_mappings) { - r = dm_cache_load_mappings(cache->cmd, - dm_cache_policy_get_name(cache->policy), + r = dm_cache_load_mappings(cache->cmd, cache->policy, load_mapping, cache); if (r) { DMERR("could not load cache mappings"); -- cgit v1.2.3